For many years, film cameras have been known which can be “dry fired”, that is, the cameras can be operated without film to demonstrate camera operation in a store and to allow user practice. A similar functionality has been disclosed for hybrid film-electronic cameras.
U.S. Pat. Nos. 5,978,016 and 5,845,166 disclose hybrid cameras in which a captured electronic image is initially stored as a “working image”. The working image remains in a working memory until the next electronic image is captured, at which time the first working image is replaced. In hybrid film-digital modes, a copy of the working image is also stored in a second memory. This image in the second image memory is cropped to match the print format of a corresponding film image and, for some uses can be stored at a lower resolution. The second memory can be a removable memory unit, such as a flash memory card. When the removable second memory is not present, the camera captures an electronic image and stores that image only in working memory. This storage is only temporary, since a copy cannot be stored in the missing removable memory and the electronic image in working memory is replaced when the next electronic image is captured.
This approach has the advantage of relatively modest memory requirements, particularly as to the working memory permanently retained in the camera, since only a single image is retained in working memory. This also provides automatic overwriting of the last image when the camera is used without a second memory. This is convenient for use as a demonstration mode, in which an image is captured only to show camera operation. On the other hand, this approach is cumbersome, since the working memory is limited to the last captured electronic image and longer term storage is limited to the removable second memory.
Another approach for the storage of electronic images in memory of a hybrid camera is semi-permanent storage of multiple images and use of an overwriting queue. In this approach, every image is stored in memory and remains there indefinitely until the memory space is needed for a replacement image. This approach allows the use of more or less memory, as desired, and is also compatible with different combinations of removable and fixed memory.
It would thus be desirable to provide improved cameras and methods in which captured electronic images are all subject to semi-permanent storage and a demonstration mode is also provided.